Headlight Relay Circuit: Description

WARNING: This page is about a different car, the 2007 Lexus ES 350. However, it is still accessible from the selected car via links, so may be relevant.

The main body ECU receives a signal from the light control switch, and turns on the low beam headlights.

HINT:

The headlight relays are installed in the power distributor, so unlike conventional relays, it cannot be removed for inspection.
If only a low beam headlight bulb on one side does not illuminate, inspect the bulb, fuse, or wire harness that is related to the bulb.
If both right and left low beam headlights do not illuminate when the light control switch is turned to the HEAD position, read the light control switch HEAD signal value in the data list and perform the headlight relay active test to determine if the malfunction exists on either the switch side or the relay side.